1. The Field of the Invention
The present invention relates to methods and apparatus for use in the autotransfusion of blood. More particularly, the present invention relates to an improved autotransfusion system which minimizes the amount of air in contact with the blood such that hemolysis is minimized.
2. The Background of the Invention
It has generally been accepted in the art that when dealing with a situation in which a person loses a significant quantity of blood, it may be necessary to transfuse homologous blood to the individual as part of the individual's treatment. That is, blood from a donor is injected into the patient's system in order to compensate for blood lost.
It will be readily appreciated that blood transfusions are generally required in several different definable contexts. For example, a serious trauma and resulting loss of blood may dictate that additional blood be transfused to the patient as a part of the patient's treatment. Similarly, in the context of serious and traumatic surgery, such as heart surgery, it is generally necessary to add blood to the patient's system to make up for blood loss during the surgical procedure.
In the case of both surgery and trauma, additional blood loss will at times be encountered during the recovery period. As a result, it is possible that the blood lost following surgery or trauma may require replacement. Traditionally, in each of these settings, replacement blood is obtained from a donor and then injected into the patient using various known techniques depending on whether the patient is at that time undergoing surgery or is recovering postoperatively.
Several problems have recently developed in the general area of transfusing blood. One such problem is that donor blood is becoming more and more scarce. With the increase in demand for homologous blood there has been a corresponding decrease in the amount of donor blood available. As a result, it is at times difficult to obtain the blood necessary to complete needed transfusions. In the event blood is found available, the cost of that blood is generally quite great. Thus, a blood transfusion can add significantly to the cost of treating a patient.
Additionally, certain adverse reactions have been experienced when using homologous blood. For example, immune and allergic reactions are possible in certain cases. Such reactions can have serious adverse effects on a patient's recovery. Likewise, homologous blood can at times carry certain diseases.
For example, hepatitis is commonly transmitted through homologous transfused blood. There is also considerable concern about the transmission of other serious diseases, such as, for example, acquired immune deficiency syndrome (AIDS) and malaria.
As a result of the problems discussed above, the possibility of providing autotransfusion of autologous blood has received increasing attention. Autologous blood is generally comprised of blood lost or donated by the patient himself which is reintroduced into the patient as needed during the surgical procedure or the postsurgical recovery period.
It is interesting to note that autotransfusion was first discussed in the literature as early as 1818, and was strongly recommended at various times in the late 1800's. Since the introduction of the concept of autotransfusion, its popularity has varied. Because of the problems discussed above, however, interest in autotransfusion is now again on the increase.
Along with the increased interest in autotransfusion has come an increased number of studies on the feasibility of autotransfusion. In general, it is found that autotransfusion is a relatively effective way of providing transfused blood during surgical procedures, trauma, and the postsurgical recovery.
A problem which has existed in the art, however, relates to providing an effective and acceptable apparatus for collecting autologous blood and reinfusing that blood into the patient. In attempting to provide such an apparatus, a variety of systems and blood collection containers have been developed. Generally, the containers are designed for use with shed mediastinal or thoracic blood. Blood from these sources, of course, is collected during cardiac surgery or after severe trauma to the chest region.
Most of the known devices for use in autotransfusion are simple containers. In addition, it has been quite popular in the past to provide a container which is placed in communication with a source of vacuum. As a result, the blood is drawn into the container from the surgical or trauma area.
Some containers of this general sort have been modified by placing disposable liners within the interior of the container and then providing a vacuum to drive the blood into the disposable liner. This type of container, however, is conventionally used to collect blood and other fluids for dispoal rather than reinfusion.
In certain instances it has been found necessary to separate non-blood fluids from the blood collected. As a result, certain containers have been developed which have a collection container for blood and a separate collection container for other types of fluids. These containers, however, operate on the same general principle of simply sucking fluid into the container under vacuum.
While various configurations of devices have been developed, the basic principles of operation have essentially remained the same. That is, blood is forced into the device under a high vacuum with a large air flow across the blood-air interface. The collection device is simply a container used to collect the blood. Once the blood is collected within the container, it is then either immediately reinfused, transferred to a separate container and then reinfused, or discarded.
It will be appreciated that one of the serious problems in the art, particularly when using flexible or collapsible containers, is with respect to maintaining the container in an open position so that the blood can flow into the container. Some existing containers have been either mechanically opened using stays or they have been opened by using a high external vacuum.
The result of maintaining the flexible container in the open position is, however, that blood flowing into the container will contact and mix with air as it is collected. It is well known in the art that the mixing of blood and air can result in severe hemolysis, fibrin clotting, and/or the production of emboli including air emboli.
It can be appreciated from the above discussion that one of the severe problems in prior art devices is the damage to the blood collected. As mentioned above, this damage may take the form of hemolysis, clot formation, or "drying" of the blood as it is collected. One of the factors in causing the damage to the blood is the high vacuum under which the many of existing devices operate, coupled with extensive mixing between air and blood within the system. This mixing results in damage to the blood, rupture of blood cells, and protein denaturation.
Another problem in existing autotransfusion systems is in providing adequate filtering of the blood once it is collected. As can be appreciated from the discussion above, it is not unusual for emboli to be found within collected blood. As a result, it is critical that adequate filtering be provided. Most of the prior art devices, however, have difficulty providing necessary blood filtering.
A further problem which has arisen in the art is that the blood collection devices are not of a conventional uniform type. That is, operating room and other medical personnel are not generally familiar with the devices and with their operation. Such lack of familiarity with the collection device can lead to an increased possibility of technical error in the collection and reinfusion of blood.
Similarly, many prior art devices fail to provide adequate visual monitoring of the collection and reinfusion procedure. This is generally caused by opaque portions of the device obstructing the view of the technician. This also results in less than ideal conditions under which to collect autologous blood and additional technical difficulty in operating the device.
It is apparent that what is needed in the art are methods and apparatus for easily and effectively collecting blood for autotransfusion purposes. Specifically, it would be an advancement in the art to provide methods and apparatus for collecting autotransfusion blood which avoided the problems discussed above. It would also be an advancement in the art to provide such methods and apparatus which minimize the air-blood interfaces during blood collection and collected blood into a collapsed blood bag.
It would be a further advancement in the art to provide an apparatus which employed a conventional blood transfer bag. It would be a related advancement in the art to provide such an apparatus which was capable of using a series of conventional blood transfer bags to collect the desired volume of blood. It would also be an advancement in the art to provide such an apparatus which provided for easy visual monitoring of the operation of the device. Such methods and apparatus are disclosed and claimed below.